The molecular structure of agrobacterium VirE2-single stranded DNA complexes involved in nuclear import
The molecular structure of agrobacterium VirE2-single stranded DNA complexes involved in nuclear import
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DOI：
10.1006/jmbi.1997.1230
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发表时间：
1997-09-05
影响因子：
5.6
通讯作者：
Wall, JS
中科院分区：
文献类型：
--
作者：
Citovsky, V;Guralnick, B;Wall, JS
DNA的核导入是农杆菌介导的植物遗传转化的核心环节。农杆菌通过将细菌转移DNA（T-DNA）的单链（ss）拷贝从其Ti（肿瘤诱导）质粒转运到植物细胞核中来消除植物宿主上的肿瘤。据推测，T-DNA核输入的过程是由两个农杆菌蛋白质，VirD 2和VirE 2，这被认为是直接与运输的T-DNA介导的。这两种蛋白质已被证明含有功能性核定位信号（NLS）。最近，VirE 2单独已被证明积极运输ssDNA进入植物细胞核。为了理解DNA核输入的过程，重要的是要知道运输中间体的结构。为此，通过扫描透射电子显微镜（STEM）分析了VirE 2和ssDNA的复合物。这个分析表明VirE 2将ssDNA包装成具有电话线样卷曲结构的半刚性中空圆柱形细丝。这些复合物的外径太大，不能通过扩散进入细胞核，但在活性核输入的尺寸排阻限度内。详细的质量分析VirE 2-ssDNA丝，并提出了一个结构模型。(C)出版社：Academic Press Limited。
Nuclear import of DNA is a central event in genetic transformation of plant cells by Agrobacterium tumefaciens. Agrobacterium elicits tumors on plant hosts by transporting a single-stranded (ss) copy of the bacterial transferred DNA (T-DNA) from its Ti (tumor-inducing) plasmid into the plant tell nucleus. Presumably, the process of T-DNA nuclear import is mediated by two agrobacterium proteins, VirD2 and VirE2, which are thought to directly associate with the transported T-DNA. Both proteins have been shown to contain functional nuclear localizations signals (NLS). Recently, VirE2 alone has been shown to actively transport ssDNA into the plant cell nucleus. To understand the process of DNA nuclear import, it is important to know the structure of the transport intermediate. To this end, complexes of VirE2 and ssDNA were analyzed by scanning transmission electron microscopy (STEM). This analysis suggests that VirE2 packages ssDNA into semi-rigid, hollow cylindrical filaments with a telephone cord-like coiled structure. The outer diameter of these complexes is too large to enter the nucleus by diffusion but is within the size exclusion limits of the active nuclear import. Detailed mass analysis of VirE2-ssDNA filaments is presented and a structural model is proposed. (C) 1997 Academic Press Limited.